If you don't have access to supplies of farmyard manure or are unable to make suitable amounts of garden compost, a green manure crop may provide the solution.
Many green manures can be sown all year round, meaning if ground becomes available after harvesting then this is the ideal time to improve the soil for the following season.
Some green manures have the ability to absorb nitrogen from the air,this is then transferred to the roots then released into the soil when it is dug in.
Another attribute is the growing plants can prevent nutrients in the soil being washed away by the winter weather.
As ground becomes vacant, hoe or fork out weeds, then rake down before broadcast sowing a green manure crop such as mustard, rape, vetch or annual lupin at a rate of around 50gms per sq.m.
A seeded area should be well covered within two to three weeks.
Allow them to grow on for around eight weeks before digging in.
If the plants start to flower before this,cut the tops of and dig them in.
Prior to digging them in, top dress the ground with Nitro-chalk, or Sulphate of ammonia, at 60gms/sq metre (2oz/sq yd)
This will prevent a temporary nitrogen shortage, and hasten the rotting down process.
Leave the green manure to decompose in the soil for up to four weeks before growing vegetables.
Sowing dates and attributes:
As ground becomes available sow;
Alfalfa: between Week 14 - 30.
It requires a growing period of around two to three months,and prefers dryish soils.
Do not sow on very wet or acidic soils.
These are deep rooted nitrogen fixing plants, and should be dug in, in the autumn or left till the following spring.
Clover: between Week 14 - 30.
Prefers light to loamy soil.
Its heavy growth tends to smother weeds, and is a nitrogen fixing manure.
Fenugreek: between Week 14 - 30.
Prefers slightly heavy well drained soil.
Quick growing and it produces masses of organic matter.
Lupin: between Week 14 - 28.
Prefers light slightly acid soil, although its deep root system will help to break up heavier soils.
An excellent nitrogen fixer.
Mustard: between Week 14 - 35
Will grow well in most types of soil.
It produces large quantities of organic matter making it a good soil improver.
Rye: between Week 13 - 35.
Suited to most soils including clay.
Can be left over-winter to be dug in,in spring.
Tares / Vetches: between Week 14 - 35.
Suited to heavy soils, but avoid acid or dry soils.
Useful overwintering manure as it prevents nutrient leaching.